Anthraquinone-azo dyes

ABSTRACT

The present invention relates to an azo dye of formula I, II or III: (formula I, II or III); wherein R 1  and R 2  are each independently of the other one or more divalent groups selected from alkylene, arylene, aralkylene and cycloalkylene, which may be interrupted by —O—, —S—, —NH—, —NR 8 —, —COO—, —CONH— or —CONR 9 —, wherein R 8  and R 9  are alkyl or aryl, X is —O— or —NH—, R 3  is —CN or —CONH 2 , R 4  is methyl or trifluoromethyl and R 5 , R 6 , R 7  and R 8  are each independently of the others hydrogen, halogen or —CN, to a process for the preparation thereof and to the use thereof in a method of producing mass-coloured plastics or polymeric colour particles.

The present invention relates to novel azo dyes, to a process for thepreparation thereof, and to the use thereof in a method of producingmass-coloured plastics or polymeric colour particles and as colorants inthe production of colour filters.

Dyes for mass-colouring plastics are known. For example, there aredescribed in U.S. Pat. No. 5,367,039 1,4,5,8-tetrasubstitutedanthraquinones having (meth)acryloyl groups which can be copolymerisedwith vinyl monomers and are thus suitable for the production of colouredvinyl polymers.

The dyes used until now do not, however, meet the highest requirementsin terms of light fastness and, especially, thermostability.

There is accordingly a need for novel thermostable dyes that producecolorations having a high tinctorial strength and exhibiting lightfastness, especially high-temperature light fastness, and that have goodall-round fastness properties.

U.S. Pat. No. 3,998,802 discloses 2,6-diaminopyridine-based azo dyesthat are suitable for colouring synthetic polyamides and polyestersaccording to the exhaust process and that are distinguished by goodproperties of fastness to heat setting and to light.

It has now, surprisingly, been found that specific2,6-diaminopyridine-based azo dyes are suitable for mass-colouringsynthetic polymers, yield colorations having a high tinctorial strengthand exhibiting light fastness, especially high-temperature lightfastness, and have good all-round fastness properties.

The present invention relates to an azo dye of formula I, II or III

wherein R₁ and R₂ are each independently of the other one or moredivalent groups selected from alkylene, arylene, aralkylene andcycloalkylene, which may be interrupted by —O—, —S—, —NH—, —NR₈—, —COO—,—CONH— or —CONR₉—, wherein R₈ and R₉ are alkyl or aryl,

-   X is —O— or —NH—,-   R₃ is —CN or —CONH₂,-   R₄ is methyl or trifluoromethyl and-   R₅, R₆, R₇ and R₈ are each independently of the others hydrogen,    halogen or —CN.

The substituents R₁ and R₂ may be identical or different; preferably, R₁and R₂ are identical.

Any radical denoting alkyl may be a straight-chain or branched alkylradical having preferably from 1 to 12 carbon atoms that may besubstituted by one or more hydroxy groups, amino groups or halogenatoms.

Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,neopentyl, n-hexyl, n-heptyl, n-octyl, isooctyl, n-decyl and n-dodecyl.

Substituted alkyl groups include, for example, 2-hydroxyethyl,2-hydroxypropyl, 4-hydroxybutyl, 2-aminoethyl, 2-aminopropyl,4-aminobutyl, 2-chloroethyl, 2-bromoethyl and 4-chlorobutyl.

Aryl groups as R₈ or R₉ have preferably from 5 to 24, especially from 6to 14, carbon atoms and may be substituted, for example, by C₁-C₄alkyl,C₁-C₄alkoxy, halogen or by the radical —NH—CO—R wherein R is amino,C₁-C₄alkyl, unsubstituted phenyl or phenyl substituted by C₁-C₄alkyl,C₁-C₄alkoxy or by halogen.

Examples of suitable aryl groups include phenyl, tolyl, mesityl, isityl,2-hydroxyphenyl, 4-hydroxyphenyl, 2-chlorophenyl, 4-chlorophenyl,2-aminophenyl, 3-aminophenyl, 4-aminophenyl, 4-methoxyphenyl,4-ethoxyphenyl, 4-acetylaminophenyl, naphthyl and phenanthryl.

When one of the divalent radicals R₁ or R₂ is alkylene, it is preferablya C₁-C₆alkylene group, for example ethylene, propylene, trimethylene,tetramethylene or hexamethylene.

Alkylene groups interrupted by —O— or —NH— may be poly(oxyethylene),poly(oxypropylene), poly(aminoethylene) and poly(oxypropylene), forexample —(OCH₂CH₂)_(n)—, —(OCHCH₃CH₂)_(n)—, —(NHCH₂CH₂)_(n)—,—(NHCHCH₃CH₂)_(n)—, wherein n is a number from 1 to 10.

Examples of arylene groups include 1,2-, 1,3- and 1,4-phenylene,toluene-2,4-diyl, toluene-2,5-diyl, toluene-2,6-diyl,naphthalene-1,4-diyl, naphthalene-1,5-diyl and naphthalene-1,8-diyl.

Aralkylene groups are, for example, groups of the following formulae:

Examples of cycloalkylene are 1,2-cyclopentylene, 1,3-cyclopentylene,1,2-cyclohexylene, 1,3-cyclohexylene and 1,4-cyclohexylene.

Halogen is fluorine, chlorine, bromine or iodine.

Preference is given to azo dyes of formula I, II or III wherein R₃ is—CN and R₄ is methyl.

Preference is given also to azo dyes of formula I, II or III wherein R₁and R₂ are C₂-C₈-alkylene, C₆-C₁₄arylene or C₈-C₂₂aralkylene.

Special preference is given to azo dyes of formula I, II or III whereinR₁ and R₂ are each a group of formula IV (IV),

XH being bonded to the alkylene group and X being —O—.

R₅, R₆, R₇ and R₈ are preferably hydrogen, chlorine or bromine andespecially hydrogen.

An especially preferred azo dye of formula I is the compound of formulaIa

The compounds of formula I, II or III can be prepared according to knownmethods, for example by diazotization of diaminoanthraquinone oraminoanthraquinone and a subsequent coupling reaction.

The invention relates also to a process for the preparation of an azodye of formula I, II or III which comprises diazotizing an anthraquinonecompound of formula V, VI or VII

wherein R₅, R₆, R₇ and R₈ are as defined hereinabove,in accordance with a conventional method, and then coupling to acoupling component of formula VIII

wherein R₁, R₂, R₃, R₄ and X are as defined hereinabove.

The diazotization of the diaminoanthraquinone compound oraminoanthraquinone compound is carried out in a manner known per se, forexample using nitrosylsulfuric acid in an aqueous acidic medium, forexample an aqueous hydrochloric acid medium or aqueous sulfuric acidmedium. The diazotization can, however, also be carried out using otherdiazotizing agents, for example sodium nitrite. An additional acid maybe present in the reaction medium in the diazotization procedure, e.g.phosphoric acid, sulfuric acid, acetic acid, propionic acid,hydrochloric acid or a mixture of such acids, for example a mixture ofpropionic acid and acetic acid. The diazotization is advantageouslycarried out at temperatures from −10 to +30° C., e.g. from 0° C. to roomtemperature.

Coupling of the diazotized anthraquinone derivative to the couplingcomponent of formula VIII is likewise carried out in known manner, forexample in an acidic, aqueous or aqueous-organic, medium, advantageouslyat temperatures from −10 to 30° C., especially below 10° C. The acidused may be, for example, hydrochloric acid, acetic acid, propionicacid, sulfuric acid or phosphoric acid.

The coupling components of formula VIII are known or can be prepared ina manner known per se, for example by reacting a 2,6-dichloropyridinederivative of formula IX

wherein R₃ and R₄ are as defined hereinabove,simultaneously or in succession, with an amine of formula X and an amineof formula XIHX—R₁—NH₂  (X),HX—R₂—NH₂  (XI),wherein R₁ and R₂ are as defined hereinabove.

The compounds of formula IX and the amines of formulae X and XI areknown and can be prepared in a manner known per se.

The invention relates also to a method of producing coloured plastics orpolymeric colour particles which comprises mixing a high molecularweight organic material with a tinctorially effective amount of at leastone azo dye of formula I, II or III.

The colouring of the high molecular weight organic substances using anazo dye of formula I, II or III can be carried out, for example, byusing roll mills, mixing apparatus or grinding apparatus to admix such adye with such substrates, the dye being dissolved or finely distributedin the high molecular weight material. The high molecular weight organicmaterial with the admixed dye is then processed according to methodsknown per se, such as, for example, calendering, compression moulding,extrusion, coating, spinning, pouring or injection moulding, as a resultof which the coloured material acquires its final form. Admixture of thedye can also be effected immediately prior to the actual processingstep, for example by simultaneously continuously feeding, directly intothe intake zone of an extruder, a solid, for example pulverulent, dyeand a granulated or pulverulent high molecular weight organic materialand, where appropriate, also other ingredients, such as additives, theconstituents being mixed in just before being processed. Generally,however, preference is given to mixing the dye into the high molecularweight organic material beforehand, since more uniformly colouredsubstrates can be obtained.

In order to produce non-rigid shaped articles or to reduce theirbrittleness, it is frequently desirable to incorporate so-calledplasticisers into the high molecular weight compounds prior to shaping.There may be used as plasticisers, for example, esters of phosphoricacid, phthalic acid or sebacic acid. In the method according to theinvention, the plasticisers can be incorporated into the polymers beforeor after the incorporation of the colorant. It is also possible, inorder to achieve different colour shades, to add to the high molecularweight organic substances, in addition to the azo dye of formula I, IIor III, also other pigments or other colorants in the desired amounts,optionally together with further additives, for example fillers orsiccatives.

Preference is given to the colouring of thermoplastic plasticsespecially in the form of fibres. Preferred high molecular weightorganic materials that can be coloured in accordance with the inventionare very generally polymers having a dielectric constant ≧2.5,especially polyester, polycarbonate (PC), polystyrene (PS), polymethylmethacrylate (PMMA), polyamide, polyethylene, polypropylene,styrene/acrylonitrile (SAN) or acrylonitrile/butadiene/styrene (ABS).Polyester and polyamide are especially preferred. More especiallypreferred are linear aromatic polyesters, which can be obtained bypolycondensation of terephthalic acid and glycols, especially ethyleneglycol, or condensation products of terephthalic acid and1,4-bis(hydroxymethyl)cyclohexane, for example polyethyleneterephthalate (PET) or polybutylene terephthalate (PBT); alsopolycarbonates, e.g. those obtained fromα,α-dimethyl-4,4-dihydroxy-diphenylmethane and phosgene, or polymersbased on polyvinyl chloride and also on polyamide, for example polyamide6 or polyamide 6.6.

Since the compounds of formulae I, II and III according to the inventioncontain at least 4 active H atoms (two NH and two XH groups), mixing thedye with the monomers and incorporation thereof in the form of acomonomer directly into the polymer skeleton is possible, provided thatthe monomers contain reactive groups that react with the active hydrogenatoms of the NH or OH groups. Examples of such monomers include epoxides(epoxy resins), isocyanates (polyurethanes) and carboxylic acidchlorides (polyamides, polyesters).

The invention accordingly relates also to a method of producing colouredplastics or polymeric colour particles that comprises causing a mixturecomprising at least one monomer that contains at least one NH- orOH-reactive group and is capable of polymerisation, polyaddition orpolycondensation reactions to react with at least one compound offormula I, II or III.

The present invention relates also to the use of compounds of formula I,II or III in the production of mass-coloured plastics or polymericcolour particles and to the plastics and polymeric colour particlescoloured using the compounds of formula I, II or III.

The dyes according to the invention impart to the above-mentionedmaterials, especially polyester materials, level colour shades of hightinctorial strength that have good in-use fastness properties,especially very good high-temperature light fastness.

The dyes according to the invention can also readily be used togetherwith other dyes to produce blended shades.

The azo dyes of formulae I, II and III according to the invention arefurthermore suitable as colorants in the production of colour filters,especially for visible light in the range from 400 to 700 nm, for liquidcrystal displays (LCDs) or charge combined devices (CCDs).

The production of colour filters by sequential application of a red,blue and green colorant to a suitable substrate, for example amorphoussilicon, is described in GB-A 2 182 165. The colour filters can becoated, for example, using inks, especially printing inks, that comprisethe azo dyes according to the invention, or can be produced, forexample, by blending the azo dyes according to the invention withchemically, thermally or photolytically structurable high molecularweight material. The further production can be carried out, for example,analogously to EP-A 654 711 by application to a substrate, such as anLCD, followed by photo-structuring and development. Other documents thatdescribe the production of colour filters include U.S. Pat. No.5,624,467, Displays 14/2,115 (1993) and WO 98/45756.

The colour filters that are produced for liquid crystal displays (LCDs)using the azo dyes according to the invention are distinguished by hightransmission of colour dots.

The invention relates also to the use of an azo dye according to theinvention as a colorant in the production of colour filters.

The following Examples serve to illustrate the invention.

I. PREPARATION EXAMPLES

I.1 Compound of formula Ia

A. Synthesis of2,6-bis[4-(2-hydroxyethyl)phenylamino]-3-cyano-4-methylpyridine 495.0 gof 2-(4-aminophenyl)-ethanol are introduced into a plane-ground flaskand heated to 140° C. There are introduced into the melt, at 120-140°C., first 255.8 g of sodium carbonate and then 190.8 g of2,6-dichloro-3-cyano-4-methylpyridine. The reaction mixture is stirredfor 18 hours at 190-195° C., and then added in portions to 1 litre of 2Nhydrochloric acid and left to stand overnight. The precipitate isfiltered off, washed and dried in a vacuum drying cabinet.

Yield: 380.8 g (98%)

B. Diazotization with 2,6-diaminoanthraquinone

14.4 g of 2,6-diaminoanthraquinone are introduced into 75 ml ofconcentrated sulfuric acid in the course of 10 min. so that thetemperature of the mixture does not exceed 40° C. After stirring for 30min. at RT, 21.6 ml of 40% nitrosylsulfuric acid are slowly addeddropwise in such a manner that the temperature is 22-25° C. (approx. 20min.). The mixture is then stirred for 4 hours at RT, a brown solutionof the diazonium salt being obtained.

1.5 litres of glacial acetic acid are introduced, as the initial charge,into a 6 litre glass beaker equipped with a pH meter; with stirring, 48g of 2,6-bis[4-(2-hydroxyethyl)phenylamino]-3-cyano-4-methylpyridine areintroduced. After the addition of 750 ml of ice-water, the solution ofthe diazonium salt is added dropwise in the course of about 10 min. ThepH is adjusted to 0.25 by adding 240 ml of 30% sodium hydroxidesolution; the temperature of the reaction mixture is not to exceed 35°C. in the course of that addition. The solution is then stirred for 4hours at 45-50° C. and overnight at RT. The precipitate is filtered off,washed with 80% acetic acid, water, dimethylformamide (DMF) and againwith water, and dried in a vacuum drying cabinet at 60-70° C.

Yield: 57.2 g (92%)

II. APPLICATION EXAMPLES

II.1. Production of a Colour Filter for Liquid Crystal Displays (LCDS)

In a 100 ml glass vessel containing 83.3 g of zirconium ceramic beads,2.8 g of the azo dye according to Example I.1, 0.28 g of Solsperse®5000, 4.10 g of Disperbyk® 161 (dispersing agent, 30% solution of a highmolecular weight block copolymer, containing groups having affinity forthe pigment, in n-butyl acetate/1-methoxy-2-propyl acetate 1:6, BYKChemie) and 14.62 g of 1-methoxy-2-propyl acetate (MPA) are stirred at23° C. for 10 minutes at 1000 rev/min. and for 180 minutes at 3000rev/min. using a Dispermat. After the addition of 4.01 g of an acrylatepolymer binder (35% solution in MPA), stirring is carried out at roomtemperature for 30 minutes at 3000 rev/min. Following removal of thebeads, the dispersion is diluted with an equal weight of MPA.

Using a spin-coating apparatus, a glass substrate (Corning type 1737-F)is coated with the resulting dispersion and centrifuged for 30 secondsat 1000 rev/min. The layer is dried on a hot plate for 2 minutes at 100°C. and for 5 minutes at 200° C. The resulting layer thickness is 0.4 μm.

The following azo dyes (Tables 1-15), which are likewise suitable formass-colouring plastics, can be prepared analogously to Example I.1:TABLE 1

R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 2

R′₁ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 3

R₁′ = R₂′ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH,—NH—CH₂—CHOH—CH₂—OH, —NH—(CH₂CH₂)—S—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂,—NH—CH₂—CON(CH₂CH₂OH)₂, —NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 4

R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 5

R′₁ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 6

R′₁ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 7

R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 8

R′₁ = R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH,—NH—CH₂—CHOH—CH₂—OH, —NH—(CH₂CH₂)—S—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂,—NH—CH₂—CON(CH₂CH₂OH)₂, —NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 9

R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 10

R′₁ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 11

R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 12

R′₁ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 13

R₁′ = R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH,—NH—CH₂—CHOH—CH₂—OH, —NH—(CH₂CH₂)—S—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂,—NH—CH₂—CON(CH₂CH₂OH)₂, —NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 14

R′₂ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

TABLE 15

R′₁ = —NH—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—O—(CH₂CH₂)—OH, —NH—CH₂—CHOH—CH₂—OH,—NH—(CH₂CH₂)—S—(CH₂CH₂)—OH, —NH—(CH₂CH₂)—NH—(CH₂CH₂)—OH,—NH—(CH₂CH₂)—NH₂, —NH—CH₂—CHOH—CH₂—NH₂, —NH—CH₂—CON(CH₂CH₂OH)₂,—NH—CH₂CH₂—CON(CH₂CH₂OH)₂,

1. An azo dye of formula I, II or III

wherein R₁ and R₂ are each independently of the other one or moredivalent groups selected from alkylene, arylene, aralkylene andcycoloalkylene, which may be interrupted by —O—, —S—, —NH—, —NR₈—,—COO—, —CONH— or —CONR₉—, wherein R₈ and R₉ are alkyl or aryl, X is —O—or —NH—, R₃ is —CN or —CONH₂, R₄ is methyl or trifluoromethyl and R₅,R₆, R₇ and R₈ are each independently of the others hydrogen, halogen or—CN.
 2. An azo dye of formula I, II or III according to claim 1, whereinR₃ is —CN and R₄ is methyl.
 3. An azo dye of formula I, II or IIIaccording to claim 1, wherein R₁ and R₂ are C₂-C₈alkylene, C₆-C₁₄aryleneor C₈-C₂₂aralkylene.
 4. An azo dye of formula I, II or III according toclaim 1, wherein R₁ and R₂ are a group of formula IV

XH being bonded to the alkylene group and X being —O—.
 5. The azo dye offormula Ia according to claim 1


6. A process for the preparation of an azo dye of formula I, II or IIIaccording to claim 1, which comprises diazotizing an anthraquinonecompound of formula V, VI or VII

wherein R₅, R₆, R₇ and R₈ are as defined in claim 1, in accordance witha conventional method, and then coupling to a coupling component offormula VIII

wherein R₁, R₂, R₃, R₄ and X are as defined in claim
 1. 7. A method ofproducing coloured plastics or polymeric colour particles that comprisesmixing a high molecular weight organic material with a tinctoriallyeffective amount of at least one azo dye of formula I, II or IIIaccording to claim
 1. 8. A method of producing coloured plastics orpolymeric colour particles that comprises causing a mixture comprisingat least one monomer that contains at least one NH- or OH-reactive groupand is capable of polymerisation, polyaddition or polycondensationreactions to react with at least one compound of formula I, II or IIIaccording to claim
 1. 9. (canceled)
 10. Plastics or polymeric colourparticles coloured in accordance with a method according to claim
 7. 11.(canceled)
 12. Plastics or polymeric colour particles coloured inaccordance with a method according to claim
 8. 13. A method of producingcolour filters that comprises coating a substrate with a high molecularweight organic material that contains a tinctorially effective amount ofat least one compound of formula I, II or III according to claim 1.